Why the iron magnetization in Gd2Fe14B and the spontaneous magnetization of Y2Fe14B depend on temperature differently

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.It is demonstrated that the temperature dependence of the iron sublattice magnetization in Gd2Fe14B is affected significantly by the Gd-Fe exchange interaction. This is at variance with the common perception that MFe(T) in iron-rich rare-earth intermetallics is determined predominantly by the Fe-Fe exchange. This phenomenon is discussed by considering the modification of the low-energy spin-wave spectrum of Gd2Fe14B, as compared to that of Y2Fe14B, under the influence of the Gd-Fe interaction. The result is of particular significance for evaluating the temperature dependence of the magnetocrystalline anisotropy of iron or cobalt compounds with anisotropic rare earths (e.g., Nd2Fe14B) and in turn, of the hard magnetic properties of such compounds